#include <iostream>
using namespace std;
int main()
{
int i,x,y,n,ans=0;
for(i=50;i<=60;i++)
{
x=i%10;
y=i/10;
n=x*10+y;
if(i+n<100)ans++;	
}
cout <<ans<<endl;
return 0;	
}
//输出6
